1. Field of the Disclosure
This disclosure relates generally to apparatus and methods for determining a compass direction and, in particular, for determining a compass direction downhole.
2. Background of the Art
Oil wells (also referred to as wellbores or boreholes) are drilled with a drill string that includes a tubular member (also referred to as a drilling tubular) having a drilling assembly (also referred to as bottomhole assembly or “BHA”) which includes a drill bit attached to the bottom end thereof. The drill bit is rotated to disintegrate the rock formation to drill the wellbore and thus enable completion of the borehole. The BHA and the tubular member include devices and sensors for providing information about a variety of parameters relating to the drilling operations (drilling parameters), the behavior of the BHA (BHA parameters) and the formation surrounding the wellbore being drilled (formation parameters). The devices and sensors use power to perform measurements. A large number of currently drilled wellbores are deviated wellbore and horizontal wellbores. The BHA used for drilling such wellbores usually includes one or more devices configured to steer the BHA so as to drill the deviated/horizontal wellbore sections. The BHA includes one or more devices that provide reference positions that are used by a controller or processor to steer the BHA.
The disclosure herein provides apparatus to determine the direction east that may be utilized to perform an operation downhole, including steering the BHA along a selected direction.